ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

INFLUENCE OF HARVESTING AND RESIDUES ON
FUELS AND FIRE MANAGEMENT
Timber harvesting produces frrest fuels with fire behavior potentials of
great concern to land managers. Fires involving slash fuels can be particularly
difficult to control, generate high costs of suppression and threaten resource
values. Fuel quantities from harvesting vary substantially and can be excessive,
depending on volumes cut and methods of harvest (Howard 1973; Benson and Johnston
1976). Util ization standards and methods of skidding offer the manager opportunities
to modify fuel hazards, because they influence fuel loading, size distribution,
conti nu5 ty, and compactness.
Little has been documented on the extent to which harvesting methods can
alter fuel characteristics and fire potentials. However, techniques developed
over the past few years for measuring and predicting fuels and flre behavior have
made it possible to appraise slash fuels. This paper describes how different
harvesting methods altered fuels and fire potential on two study areas and discusses
how managers can appraise fuels on any cutting area before slash is created.
CASE STUDIES AT UNION PASS AND CORAM
Study Procedures
Effects of harvesting on fuel and fire behavior potential were evaluated at
two locations: Union Pass on the Bridger-Teton National Forest in Wyoming, and
Coram Experimental Forest on the Flathead National Forest in Montana. Forest
conditions and study designs were different.
UNION PASS
Two mature, even-aged lodgepole pine stands were studied. In each stand, two
20-acre harvesting units were established. One unit was clearcut to "conventional I'
util izatian standards, the other to utilization standards that were called "near-
completeI1 . On both the conventional and near-compl ete harvesting units a1 1 sound
trees to a merchantable top diameter of 6 inches were removed. In addition, on
the near-complete unlts chips were produced from: (a) tops of all merchantable
trees; (b) a ll remaining live and dead sound standing trees with a d.b,h. of 3
inches or larger; and (c) a11 material remaining on the ground that was more than
6 inches in diameter at the larger end, more than 6 feet long, and sound enough to
permit skidding. On the conventional units, trees were limbed and bucked where
felled, then skidded by crawler tractor to the landing. On the near-complete
units, trees were felled and then bunched and skidded to a central point where the
sawlog material was removed. The remaining top material was then skidded to the
chipper.